science-requirements creep from being the primary driver in mission design and development, a situation that has led to near-catastrophic cost estimate growth with some of the current decadal survey missions.3

Although the 2007 decadal survey presented a number of strategies and rules to help alleviate potential budgetary pressures placed on the Earth science program and implementation of the survey missions (Appendix B), more proscriptive decision rules and /or an explicit recommendation to implement missions via a cost-constrained approach might have been more useful in giving program managers a clearer idea of how to proceed to accomplish science objectives and maintain a healthy and balanced portfolio in the face of program adversity. The committee also recognizes, however, that the NASA Earth science program must retain its flexibility to deal with the many shorter-term challenges and opportunities that arise over the course of a decade while community priorities are being implemented.

OTHER CONSIDERATIONS FOR FUTURE REVIEWS

As NASA proceeds with implementation of the current decadal survey mission portfolio, there are actions that the agency can perform now to prepare for future major programmatic reviews and priority-setting exercises. The committee suggests that NASA work proactively to identify the potential for value-added international partnerships ahead of, and separately from, future programmatic reviews. Similarly, opportunities to satisfy science objectives in non-traditional ways (e.g., constellation approaches, hosted payloads, suborbital campaigns) should be given due consideration. Such early preparatory work would help future committees and/or decision makers more easily identify synergies and potential cost savings as they craft a new mission queue.

3The CLARREO mission, for example, was recommended as a small mission and had grown to a large mission before being tabled for further formulation work prior to implementation.



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